Braille is a literary medium designed to assist visually impaired people to communicate in a written form. Standard Braille is based on tactile symbols each comprising combinations of up to six dots on a 2 by 3 matrix which can be embossed onto paper, each symbol relating to a character. Original Braille embossers comprised mechanical devices with six keys each relating to one of the six dots. A Braille page typically has up to 40 Braille symbols per line and 25 lines per page.
In some languages, for example in English, French and German, there are two grades of Braille. In Grade 1 each letter of the standard alphabet translates directly to a Braille symbol which is formed by the array of 2×3 dots, sometimes referred to as a Braille cell. There are special symbols and combinations of symbols for capitalisation, punctuation, numerals and so forth. Grade 2 Braille comprises grade 1 and, in English, 189 contractions. For example the Grade 1 symbol for the letter “b” becomes “but” if it is preceded and followed by spaces. Similarly “k” becomes “knowledge”. Special symbols exist for the common letter groups such as “ed,” “ch”, “gh” and so on.
In addition to being embossed onto paper, Braille may be created and stored electronically and displayed on a refreshable Braille display. The Braille display is similar to a short line of embossed Braille and is read in the same manner. Electronic Braille displays are comprised of cells with the same pattern of dots as embossed Braille. Modern electronic Braille displays comprise a linear array of up to 80 identical Braille cells using piezzo-electric crystals. Each dot of each cell is actuated by a piezzo electronic crystal that bends up to raise a pin (dot present) or bends down to lower the pin (dot absent). To facilitate use of Braille in computer environments, computer Braille has been developed in both six and eight dot versions. For the eight dot version two extra dots are arranged with the standard size dots in a 2 by 4 pattern to represent additional characters used in computer environments, for example the ASCII character set. The extra dots are associated with two more keys on the Braille keyboard.
Braille notetakers are portable electronic devices which assist visually impaired people to create, manage and exchange information in a manner similar to those people who use standard personal digital assistants (PDAs). A typical Braille notetaker provides applications such as a word processor, address list, day planner, phone book and the like, and has various input and output devices for operating the software, for example, a Braille keyboard, standard keyboard, tactile Braille display and synthesised voice output. Documents created using these applications can be edited, printed, emailed and saved as required.
Often a user of a Braille notetaker needs to exchange documents with users of standard word processing programs operating on computers or PDAs. Such documents however do not translate well between the two environments as much of the document formatting, such as page layout, character attributes and the like is lost. For example a Braille document has a standard layout which differs from that of documents created and saved using well known word processors such as Microsoft Word™ or WordPerfect™. The rich text of such a word processor document, along with layout features such as tables and tabs are also lost in translation. Further, documents created in one of the environments are always not suitable for use in the other environment. For example special features which are provided in a document by a Braille notetaker to assist visually impaired people to use the document are lost in translation to a word processor format. It would be desirable therefore to have a notetaker which assist the use of electronic documents in both a Braille and word processor environment.